As clarification, note that showing your license for volunteering is not the same as showing license for visiting. For visiting, your license is run through RAPTOR, a sex offender database, on the spot. For volunteering, your license is used by HISD for a criminal background check. The background check takes up to two weeks to complete. It must be repeated every year.

Following that, you will be able to join in the on-campus Carnegie community and/or volunteer on any Houston ISD campus.